Monitoring method for furnace apparatus

ABSTRACT

The present invention relates to a monitoring method for a furnace apparatus. The monitoring method includes powering on the furnace apparatus to a specific power value; recording the rate of increase of the temperature of the furnace apparatus; and comparing the rate of increase of the temperature with a predetermined threshold value, wherein the furnace apparatus is to be replaced when the rate of increase of the temperature of the furnace apparatus is less than the predetermined threshold value.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority from R.O.C. Patent Application No. 093133085, filed Oct. 29, 2004, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a monitoring method for a furnace apparatus, and more particularly to a monitoring method for determining whether the furnace apparatus should be replaced or not.

In the Semiconductor Technology Fabrication facilities, the furnace apparatus for heating is a very important and necessary apparatus. The furnace apparatus is mainly made of Quartz, which is able to endure high temperature and high pressure. The furnace apparatus employs heating theorem of ultrared radiation, heat convection and heat conduction to let the surrounding of the silicon wafer and whole furnace apparatus reach heat-balance, so as to precisely control the temperature of the silicon wafer and heat a large amount of silicon wafers at the same time. Obviously, the furnace apparatus is suitable for the traditional Batch Process and have the advantages in reducing the time of fabrication and cost.

Conventionally, the furnace apparatus has horizontal type and vertical type, which is utilized for oxidation process, diffusion process, annealing process, sintering process and Low Pressure-Chemical Vapor Deposition System process. For example, the most important processes of forming thermal oxidation of the gate oxide layer in the Semiconductor Technology just needs to employ the furnace apparatus.

The vertical furnace apparatus introduced in the early 1990's decreases the required space of the clean room and improves the operation of automation process, which are the main differences to the horizontal furnace apparatus. The vertical furnace apparatus has five main parts, which are process chamber, wafer transfer system, gas distribution system, departing system and temperature controlling system. FIG. 1 is a schematic view showing a structure of a conventional vertical furnace apparatus. As shown in FIG. 1, the vertical furnace apparatus 1 at least includes a quartzware 11 and heating coils 12. The heating coils 12 are kinds of metal resistances and surround the outer surface of the quartzware 11 for affecting the heating area to be heated uniformly. After a period of uses, the heating coils 12 will typically become deformed, so as to increase the resistance value more and more. However, under the condition of same power provided, according to Ohm's law, which shows the power has an inverse ratio to the resistance value, the temperature ramp rates of the furnace apparatus will be decreased while the resistance value is increased, and the furnace apparatus will be less and less efficient. In general, the method to determine whether the furnace apparatus should be replaced or not is to observe the degree of the deformation of the heating coils 12. Because the heating coils 12 are disposed in the interior of the furnace apparatus, however, the status of the heating coils 12 cannot be observed in ordinary process. Only when the furnace apparatus is stopped or when the Preventive Maintenance Cycle (PM cycle) is due can the status of the heating coils 12 be observed visually, and then the next step is to determine whether the furnace apparatus should be replaced with a new one or not. However, the error may be great if the decision is inaccurately made upon visual observation, which may be quite common. Further, in practice, the life of the heating coils 12 is difficult to ascertain if the heating coils 12 are used in different voltage and current ranges. If the survey of the heating coils 12 is made according to Preventive Maintenance Cycle (PM cycle), the efficiency of the heating coils 12 may already be insufficient, or the deformation of the heating coils 12 is so large that the furnace apparatus would be shut down suddenly. On the other hand, if the furnace apparatus is replaced frequently, the cost of the whole facilities will be increased which may be impractical.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention provide a monitoring method for efficiently determining whether the furnace apparatus should be replaced or not, so that operation of the furnace apparatus does not need to be stopped.

A feature of the present invention is to provide a monitoring method of furnace apparatus, which allows the operators to retrieve the rate of increase of the temperature of the furnace apparatus when the furnace apparatus is in operation and allows the operators to determine whether the furnace apparatus should be replaced or not without stopping the furnace apparatus or waiting till the PM cycle is due. Further, the monitoring method of furnace apparatus according to the present invention keeps stable the rate of increase of the temperature of the furnace apparatus and prevents unnecessary waste of cost.

In accordance with an aspect of the present invention, a monitoring method of furnace apparatus includes: powering on the furnace apparatus to a specific power value; recording the rate of increase of the temperature of the furnace apparatus; and comparing the rate of increase of the temperature with a predetermined threshold value; wherein the furnace apparatus is to be replaced if the rate of increase of the temperature of the furnace apparatus is less than the predetermined threshold value.

In an embodiment, the specific power value is substantially 100% of the maximum power. In an embodiment, the heating coil of the furnace apparatus is metal resistance. In an embodiment, the furnace apparatus includes at least a quartzware and a plurality of heating coils. In an embodiment, the heating coils of the furnace apparatus surround the outer surface of the quartzware. In an embodiment, the heating coils of the furnace apparatus form a plurality of heating areas. In an embodiment, the predetermined threshold value is about 15° C./MIN. In an embodiment, the furnace apparatus is selected from vertical furnace apparatus and horizontal furnace apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a structure of a conventional vertical furnace apparatus; and

FIG. 2 is a flow chart showing the steps of the monitoring method of furnace apparatus according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of specific embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.

The present invention is directed to a monitoring method of furnace apparatus. Such a monitoring method can monitor the rate of increase of the temperature of the furnace apparatus, so as to determine whether the furnace apparatus should be replaced or not, in order to increase the efficiency of the furnace apparatus and save cost.

FIG. 2 is a flow chart showing the steps of the monitoring method of furnace apparatus according to one embodiment of the present invention. As shown in FIG. 2, in step S1, the furnace apparatus is powered on to a specific power value, preferably at about 100%, to let the furnace apparatus be heated at full speed. Then, in step S2, a temperature recording device is employed to record the rate of increase of the temperature of the furnace apparatus, in ° C./MIN unit. Meanwhile, in step S3, an operator can compare the rate of increase of the temperature of the furnace apparatus with a predetermined threshold value. When the rate of increase of the temperature of the furnace apparatus is less than the predetermined threshold value, it will be deemed that the resistance of the furnace apparatus has been too low and cannot be used anymore. In that case, in step S4, the operator can replace the furnace apparatus.

In the embodiment shown, the predetermined threshold value can be determined according to the accumulated experience values. More particularly, the predetermined threshold value can be determined by the following steps. First, check the furnace apparatus, which is heated at full speed, once every day or every 2˜3 days within one time period such as 2˜3 years to record the rate of increase of the temperature of the furnace apparatus. Then, plot a curve showing the relationship between time and the rate of increase of the temperature of the furnace apparatus. Next, define a specific value as the predetermined threshold value for determining whether the furnace apparatus should be replaced or not. After a period of uses, the heating coils become deformed, so as to increase the resistance value more and more. However, under the condition of same power provided, according to Ohm's law, which shows the power has an inverse ratio to the resistance value, the temperature ramp rates of the furnace apparatus will be decreased while the resistance value is increased, and the furnace apparatus will be less and less efficient. When the furnace apparatus is replaced with a new one, the rate of increase of the temperature of the furnace apparatus is obviously raised for a long time. For example, if the predetermined threshold value is set at 15° C./MIN, when the rate of increase of the temperature of the furnace apparatus is gradually slowed down near about 16° C./MIN, the user may need to pay more attention to the furnace apparatus. Once the rate of increase of the temperature of the furnace apparatus is equal to or less than 15° C./MIN, it means that the heating coils of the furnace apparatus have a resistance value over a tolerance value and it is time to replace the furnace apparatus with a new one.

The monitoring method of the present invention employs a temperature recording device to record the rate of increase of the temperature of the furnace apparatus and employs a monitor to show the recorded results so that the operator can check the rate of increase of the temperature of the furnace apparatus any time or regularly to determine whether the furnace apparatus should be replaced or not. Therefore, the operator need not shut down the furnace apparatus for checking the furnace apparatus and does not rely on visual inspection of the furnace apparatus. In addition, the monitoring method not only can prevent the furnace apparatus from shutting down suddenly and but can also prevent unnecessary waste of cost.

In an embodiment, the vertical furnace apparatus 1 at least includes a quartzware 11 and a plurality heat coils 12. The heat coils 12 are kinds of metal resistances and surround the outer surface of the quartzware 11 for affecting the heating areas to be heated uniformly. The number of the heating areas preferably ranges from 3 to 9. In addition, the predetermined threshold value may be different in various furnace apparatus. The predetermined threshold value of 15° C./M1N can be applied to TEL IW-6D vertical furnace apparatus, which is available from TOKYO ELECTRON LIMITED. Certainly, the specific power value in step S1 is not limited to 100%. Alternatively, the furnace apparatus can be heated at a constant and immovable speed and checked once every day or every 2˜3 days within one time period such as 2˜3 years to record the rate of increase of the temperature of the furnace apparatus. Then, the curve can be plotted to show the relationship between time and the rate of increase of the temperature of the furnace apparatus. Subsequently, a suitable predetermined threshold value may be defined according to the curve. In addition, the recorded values recorded by the temperature recording device can be incorporated into the recipes of other semiconductor technology fabrication facilities for allowing the operators to check the furnace apparatus regularly.

The present invention provides a monitoring method of furnace apparatus and the monitoring method of furnace apparatus allows the operators to retrieve the rate of increase of the temperature of the furnace apparatus when the furnace apparatus is in operation and allows one to determine whether the furnace apparatus should be replaced or not without stopping the furnace apparatus or waiting till the PM cycle is due. Further, the monitoring method of furnace apparatus according to the present invention keeps stable the rate of increase of the temperature of the furnace apparatus and prevents unnecessary waste of cost.

It is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. 

1. A monitoring method for a furnace apparatus, the monitoring method comprising: powering on the furnace apparatus to a specific power value; recording the rate of increase of the temperature of the furnace apparatus; and comparing the rate of increase of the temperature with a predetermined threshold value, wherein the furnace apparatus is to be replaced when the rate of increase of the temperature of the furnace apparatus is less than the predetermined threshold value.
 2. The monitoring method for a furnace apparatus of claim 1, wherein the specific power value is substantially 100% the maximum power.
 3. The monitoring method for a furnace apparatus of claim 1, wherein the furnace apparatus includes a heating coil which is metal resistance.
 4. The monitoring method for a furnace apparatus of claim 1, wherein the furnace apparatus includes at least a quartzware and a plurality of heating coils.
 5. The monitoring method for a furnace apparatus of claim 4, wherein the heating coils of the furnace apparatus surround the outer surface of the quartzware.
 6. The monitoring method for a furnace apparatus of claim 4, wherein the heating coils of the furnace apparatus form a plurality of heating areas.
 7. The monitoring method for a furnace apparatus of claim 1, wherein the predetermined threshold value is 15° C./MIN.
 8. The monitoring method for a furnace apparatus of claim 1, wherein the furnace apparatus is selected from the group consisting of a vertical furnace apparatus and a horizontal furnace apparatus.
 9. The monitoring method for a furnace apparatus of claim 1, further comprising: plotting a curve showing a relationship between time and the rate of increase of temperature of the furnace apparatus; and determining the predetermined threshold value based on the curve.
 10. The monitoring method for a furnace apparatus of claim 9, wherein the predetermined threshold value is determined for the specific power value.
 11. A monitoring method for a furnace apparatus, the monitoring method comprising: determining a threshold value by powering the furnace apparatus to a preset power value and obtaining a relationship between time and a rate of increase of temperature of the furnace apparatus; powering the furnace apparatus to the preset power value; recording the rate of increase of temperature of the furnace apparatus; and comparing the recorded rate of increase of temperature with the threshold value, wherein the furnace apparatus is to be replaced when the recorded rate of increase of temperature is less than the threshold value.
 12. The monitoring method for a furnace apparatus of claim 11, wherein the preset power value is substantially 100% the maximum power.
 13. The monitoring method for a furnace apparatus of claim 11, wherein the furnace apparatus includes a heating coil which is metal resistance.
 14. The monitoring method for a furnace apparatus of claim 11, wherein the furnace apparatus includes at least a quartzware and a plurality of heating coils.
 15. The monitoring method for a furnace apparatus of claim 14, wherein the heating coils of the furnace apparatus surround the outer surface of the quartzware.
 16. The monitoring method for a furnace apparatus of claim 14, wherein the heating coils of the furnace apparatus form a plurality of heating areas.
 17. The monitoring method for a furnace apparatus of claim 11, wherein the predetermined threshold value is 15° C./MIN.
 18. The monitoring method for a furnace apparatus of claim 11, wherein the furnace apparatus is selected from the group consisting of a vertical furnace apparatus and a horizontal furnace apparatus.
 19. The monitoring method for a furnace apparatus of claim 11, wherein obtaining a relationship between time and a rate of increase of temperature of the furnace apparatus comprises plotting a curve showing the relationship between time and the rate of increase of temperature of the furnace apparatus, and wherein the predetermined threshold value is determined based on the curve.
 20. The monitoring method for a furnace apparatus of claim 19, wherein the predetermined threshold value is determined for the preset power value. 